I agree that a good travel companion has to be flexible and on the same page about things like how many sites you want to knock down and approximately when you’ll get up each day. But another valuable quality is a good sense of humor, or, at the very least, a willingness to grab a drink.
Traveling can be tiring and things can go wrong, but if you both realize this and make snarky comments throughout, it’s great. Also, I believe the best way to experience a new place is to get away from the typical, so someone with a hard and fast list of standard tourist traps would drive me nuts. I’d rather meander, get lost, and sit in a cafe somewhere.
I’ve found that it’s best to only schedule one main thing in a day, whether it is a museum or a monument or whathaveyou. Hmm, now I really want to take an exotic trip…